Configurable pseudo dual port architecture for use with single port SRAM

ABSTRACT

A memory array has word lines and bit lines. A row decoder is operable to decode a row address and select a corresponding word line. A read-write clock generator is operable to generate a hold clock signal. An address clock generator receives a read address, a write address, a dual port mode control signal, a read chip select signal, and a write chip select signal. When operating in dual port mode, and when operating in a read mode, the address clock generator applies a read delay to the read address and outputs the read address, as delayed, to the row pre-decoder as the address in response to the hold clock signal.

TECHNICAL FIELD

This application related to the field of control circuitry for randomaccess memory, and, more particularly, control circuitry that enables asingle port SRAM to act as a dual port SRAM.

BACKGROUND

Single port memory is capable of performing a single operation, such asa read or a write, at a time. On the other hand, dual port memory iscapable of performing multiple operations, such as a read and a write,substantially simultaneously.

Dual port memory consumes substantially more chip area and issubstantially more complex and costly from development and qualificationpoint of view as compared to single port memory. This is because dualport memory typically has two separate address buses, with one being fora read address and the other being for a write address, as well as twoseparate data buses, with one being for data read out from the memoryand the other being for data written to the memory.

Due to its ability to read and write simultaneously, dual port memory istherefore desirable over single port memory for some applications.However, since the extra space consumed by dual port memory may beundesirable, designs have been derived that provide the functionality ofdual port memory while not consuming substantially more surface areathan single port memory.

These designs are known as pseudo dual port memory. However, suchdesigns come with their own drawbacks. For example, such designs tend tobe substantially slower than true dual port memory. In addition, suchdesigns lose the capability of operating in single port mode, meaningthat they cannot selectively operate in single port mode when desired.This also avoids the development of a separate compiler for single portmemory.

Therefore, it is clear that further development in the area of pseudodual port memory design is needed.

SUMMARY

This summary is provided to introduce a selection of concepts that arefurther described below in the detailed description. This summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofthe claimed subject matter.

Disclosed herein is a memory controller for a memory array having wordlines and bit lines. The memory controller includes a row decoderconfigured to decode a row address and select a word line correspondingto the decoded row address, a row pre-decoder configured to output anaddress to the row decoder as the row address, and a read-write clockgenerator configured to generate clocks to the row decoder and ainput/output (IO) block, and read or write address selection signal tostart a read or write operation depending on the mode of operation. Anaddress clock generator is configured to receive a read address, a writeaddress, a dual port mode control signal, a read chip select signal, anda write chip select signal. The address clock generator, when operatingin dual port mode as indicated by the dual port control signal, and whenoperating in a read mode as indicated by the read chip select signal, isconfigured to apply read address signal to the row pre-decoder andcolumn pre-decoder as the address. The address clock generator, whenoperating in dual port mode as indicated by the dual port controlsignal, and when operating in a write mode as indicated by the writechip select signal, is configured to apply a write delay to the writeaddress and output the write address signal-to the row pre-decoder andcolumn pre-decoder as the address, in response to the hold clock signalgenerated in the first read mode cycle. When operating in dual portmode, the hold clock generated in a write operation applies a next readaddress signal to the row pre-decoder and column address as the address.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a six transistor SRAM cell.

FIG. 2 is a system level block diagram of pseudo dual port controlcircuitry capable of converting single port memory to pseudo dual portoperation, yet maintaining the ability to revert to single port mode.

FIG. 3 is a schematic block diagram of the address clock generator ofFIG. 2.

FIG. 4 is a schematic block diagram of the address control block of theaddress clock generator of FIG. 2.

FIG. 5 is a schematic block diagram of read-write clock generator ofFIG. 2.

FIG. 6 is a schematic block diagram of the row pre-decoder of FIG. 2.

FIG. 7 is alternate single port mode control circuitry for use in FIG.2.

FIG. 8 is a timing diagram showing operation of the block diagram ofFIG. 2 in operation.

FIG. 9 is a timing diagram showing generation of the address clocksignals.

FIG. 10 is another timing diagram showing generation of the addressclock signals.

FIG. 11 is timing diagram showing a fault due to a lack of RC tracking.

FIG. 12 is a timing diagram showing prevention of the fault using RCtracking.

FIG. 13 is a timing diagram showing operation of the block diagram ofFIG. 2, switching between single and dual port modes of operation.

DETAILED DESCRIPTION

One or more embodiments of the present disclosure will be describedbelow. These described embodiments are only examples of the presentlydisclosed techniques. Additionally, in an effort to provide a concisedescription, all features of an actual implementation may not bedescribed in the specification.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features. Like referencenumbers in the drawing figures refer to like elements throughout, aswell as reference numbers with prime notation, may indicate similarelements in other applications or embodiments.

Disclosed herein is a memory controller or control circuitry thatfunctions to enable an array of six transistor SRAM cells to function ina pseudo dual-port mode. First, with reference to FIG. 1, a sample sixtransistor SRAM cell 10 is now described. The SRAM cell 10 is comprisedof six MOSFETs, M1-M6. Transistors M1-M2 form a first inverter 12, andtransistors M3-M4 form a second inverter 14. The inverters 12 and 14 arecross-coupled. Each bit of data is stored on the transistors M1-M4forming the inverters 12 and 14. Transistors M5 and M6 control access tothe memory cell 10 during read and write operations. Access to thememory cell 10 is enabled by the word line WL which controls the twoaccess transistors M5 and M6 which, in turn, control whether the memorycell 10 is connected to the bit lines BL and BL. Bit lines BL and BL areused to transfer data for both read and write operations. During readaccesses, the bit lines BL and BL are actively driven high and low bythe inverters 12 and 14, permitting readout.

With reference to FIG. 2, the control circuitry or memory controller100, as coupled to a memory array 58, is now described. The memory array58 is an array of six transistor SRAM cells, as described above withreference to FIG. 1, and includes at least one dummy column 60. Thememory array 58 is accessed via word lines WL<0:n>, and bit linesBL<0:m> and BL<0:m>.

A single port RAM control logic 52, due to its single port nature, isconfigured to either operate in read mode or in write mode. The singleport RAM control logic 52 is enabled or disabled by the chip selectsignal CSN, which is generated by coupling of a write chip select signalWCSN and a read chip select signal RCSN to AND gate 53, which passes theresult as CSN. The single port RAM control logic 52 receives the deviceclock CK.

The single port RAM control logic 52 functions to generate clock signalCKLATCH and intCK for use by the address clock generator 102 andread-write clock generator 104.

It should be understood that the memory control circuit 100 can beconfigured to operate in one of four modes. When operating inpseudo-dual port mode, RCSN and WCSN are both asserted, which in theillustrated embodiments is as a logic low. When operating in single portmode and performing a read, RCSN is asserted, while WCSN is deasserted.Similarly, when operating in single port mode and performing a write,WCSN is asserted, while RCSN is deasserted. Where no operations are tobe performed, RCSN and WCSN are both deasserted.

Port control circuitry 300 controls which mode the single port ramcontrol logic 52 is operating in, and includes a multiplexer 103controlled by a multiplexer select signal MUXSEL, that serves tomultiplex either a logic high or WCSN to inverter 105, which passes thereceived signal as the write enable signal WEN to the single port ramcontrol logic 52. When a read and a write operation are to be performed(i.e. operation in pseudo-dual port mode), the read is performed first.Therefore, where a read is to be performed, MUXSEL is low, and a logichigh is passed as WEN. If a write is to be performed after the read,WCSN will be low, and a logic low is thus passed as WEN.

Alternate port control circuitry 300′ is now described with reference toFIG. 7. Here, the port control circuitry 300′ includes NAND gate 302which performs a logical NAND operation of the single port mode signalSPMOD and the write enable signal WEN, and provides its output tomultiplexer 103. The write enable signal WEN or a logic low signal isinverted by inverter 304, and provided to multiplexer 103 as a secondinput. The multiplexer 103 provides its output through inverter 105,which passes the received signal as WEN to the single port ram controllogic 52.

The read-write clock generator 104 generates the internal signal intCKwhich initiates read and write operations depending on the mode ofoperation. HCLK is the delayed version of intCK, which is used ingeneration of the MUXSEL signal. The MUXSEL signal selects the addressto be passed inside to the row/column pre-decoders.

The read-write clock generator 104 also receives the RC (resistance andcapacitance load of metal and device) tracking signal YCLKRC-TRACK andRESET, which are used in the generation of internal clock intCK again inthe same cycle for a write operation after a read operation. TheYCLKRC-TRACK signal tracks the complete resetting of column address andIO signal of the first read operation. The RESET (selftime reset) signalis generated from dummy column block ‘60’ shown in FIG. 2, and helpsensure successful read and write operations. Using both RESET andYCLKRC-TRACK signals in generation of the second intCK avoids theoverlap of signals between read and write operation, which in turnavoids the corruption of the memory's stored data. The READY signal isgenerated using both YCLKRC-TRACK and RESET signals. Generation of READYsignal trigger intCK is performed again for the write operation, whenoperating in dual port mode.

The address clock generator 102 receives the read address RA<0:n>, ifany, where data is to be read from, and receives the write addressWA<0:n>, if any, where data is to be written to. The address clockgenerator 102 also receives a control signal SPMOD indicating whetherthe circuitry 100 is to operate in single port mode or pseudo dual portmode.

The address clock generator 102, when operating in dual port mode asindicated by SPMOD, and in read mode as indicated by RCSN, is configuredto latch the read address signal RA<0:n> and output the read addresssignal RA<0:n> to row and column pre-decoder 106, as a function ofMUXSEL. When operating in dual port mode as indicated by SPMOD and inwrite mode as indicated by WCSN, the address clock generator 102 latchesthe write address signal WA<0:n> and outputs the write address signalWA<0:n> to row and column pre-decoder 106, as a function of MUXSEL. Theaddress clock generator generates clock signals CKSB, CKMB, CKSBB, andCKMBB from clock signal CKLATCH, and outputs them to row and columnpre-decoder 106.

The row and column pre-decoder 106 serves to output the row addressreceived from the address clock generator 102 to row decoder 54, and thecorresponding column addresses to the read-write multiplexers 64, 62,for use in readout or writing to the memory array 58. The appropriatedata is then read from, or written to, the memory array 58 via the bitlines BL<0:m> and BL<0:m>.

The read-write IO control 66 controls the read-write multiplexers 64,62, and generates the RC tracking signal YCLKRC TRACK.

With additional reference to FIG. 5, in greater detail, the read-writeclock generator 104 includes a first master-slave flop chain comprisedof latches 131, 133 configured to receive WCSN and being clocked byCKLATCH and an inverse thereof, which provides output to NOR gate 139. Asecond master-slave flop chain comprised of latches 135, 137 configuredto receive RCSN and being clocked by the latch clock and the inversethereof, provides output to NOR gate 139 as well. The NOR gate 139 alsoreceives the single port mode signal SPMOD as input, and provides itsoutput to NAND gate 141.

The NAND gate 141 also receives input from an output of a master-slavelatch chain comprised of latches 143, 145 clocked by reset signal RESETand an inverse thereof. The output of NAND gate 141 is provided as inputto latch 143. NOR gate 147 receives input from latch 145, as well as theRC tracking signal YCLKRC TRACK.

PMOS transistor T1 has its source coupled to power supply node VDD, itsdrain coupled to the drain of NMOS transistor T2, and its gate coupledto the reset signal RESET. NMOS transistor has its source coupled to thedrain of NMOS transistor T3, and its gate coupled to the clock signalCK. NMOS transistor T3 has its source coupled to ground, and its gatecoupled to a delayed version of CK 149.

Latch 151 is coupled to the drain of PMOS transistor T1, as is the drainof NMOS transistor T4. NMOS transistor T4 has its source coupled toground and its gate coupled to receive the output from the NAND gate147. The internal clock signal intCK is generated at the drain of PMOStransistor T1 and drain of NMOS transistor T4, and then delayed by block153, for output as the hold clock signal HCLK.

The resulting timing of the hold clock signal HCLK, relative to thedevice clock CK and internal clock intCK signal, can be seen in FIG. 8.As can be seen, HCLK is a delayed version of intCK, and this delay isaligned with the hold time delay needed to latch the address to bewritten to or read from in the word line latches. This delay betweenHCLK and intCK is short, since the address can be changed once the holdclock HCLK causes the latching.

This effectively means that a next address can be released as soon ashold clock HCLK is generated. Since in pseudo-dual port mode a read isperformed prior to a write, this means that the write address WA<0:n>can be released, via MUXSEL, as soon as hold clock goes low during theread operation. This fast release of the write address WA<0:n> duringthe read operation helps ensure that the write address WA<0:n> settledprior to the write operation itself being triggered by the internalclock intCK. This provides a substantial increase in speed compared toprior pseudo-dual port designs.

Details of the address clock generator 102 will now be given withadditional reference to FIG. 3. The address clock generator 102 includesaddress control circuitry 110 configured to receive RCSN and WCSN, andin response thereto, generate address clock signals CKMB, CKMBB, CKSB,CKSBB, as well as MUXSEL. The address clock generator 102 includes amultiplexer configured to multiplex the latched read address signal andthe latched write address signal to the row pre-decoder as the address,under control of MUXSEL.

The address control circuit 110 itself includes an address control block112 configured to receive RCSN and WCSN, and in response thereto,generate a first clock output CKA and a write only signal WRONLY. Theblock 111 generates the clock signals CKMB, CKMBB, CKSB, CKSBB, as wellas MUXSEL from the first clock output CKA and the write only signalWRONLY.

The block 111 is comprised of a first inverter 114 receiving the firstclock output CKA and generating therefrom a second clock output CKMB. Asecond inverter 116 is coupled to receive the second clock output CKMBand to generate therefrom a third clock output CKMBB. A NAND gate 118receives the first clock output CKA and the write only signal WRONLY,and generates therefrom a fourth clock output CKSB. A third inverter 120is coupled to the output of the NAND gate 118 to generate a fifth clockoutput CKSBB.

The address control block 112, with additional reference to FIG. 4,includes OR gate 115 coupled to receive RCSN as inverted by inverter113, and WCSN. The output of OR gate 115 is the write only signalWRONLY. NAND gate 117 is coupled to receive the output from OR gate 115.

Latch 119 receives output from NOR gate 123 and is clocked by HCLK.Output of latch 119 is inverted and fed to the input of latch 121, whichis clocked by an inverse of HCLK. The NAND gate 117 receives output fromlatch 121, and produces MUXSEL at its output. OR gate 125 receives WCSNand RCSN, and provides output to NOR gate 123. NOR gate 123 alsoreceives the single port mode signal SPMOD as input, and provides outputto latch 119.

A read latch circuit 130 receives the read address RA<0:n> and latchesthe read address RA<0:n> for output to the multiplexer 160. A writemaster latch circuit 140 and write slave latch circuit 150 arrangementreceive the write address WA<0:n> for output to the multiplexer 160until completion of a write operation. As will be explained, the writeaddress WA<0:n> is latched prior to completion of the read operation, sothat when the write operation begins, the write address WA<0:n> isalready attached.

The read latch circuit 130 includes a first clocked inverter 132 havinga data input receiving the read address RA<0:n> as input, a first clockinput receiving the second clock output CKMB, and a second clock inputreceiving the third clock output CKMBB. Inverter 134 receives outputfrom the first clocked inverter 132. A second clocked inverter 136 has adata input coupled to receive output from the inverter 134, a firstclock input receiving the third clock output CKMBB, a second clock inputreceiving the second clock output CKMB, and an output coupled to themultiplexer 160.

The master write latch circuit 140 includes a first clocked inverter 142having a data input receiving a bit of the write address WA<0:n> asinput, a first clock input receiving the second clock output CKMB, and asecond clock input receiving the third clock output CKMBB. An inverter144 is coupled to receive output from the first clocked inverter 142. Asecond clocked inverter 146 has a data input coupled to receive outputfrom the inverter 144, a first clock input receiving the third clockoutput CKMBB, a second clock input receiving the second clock outputCKMB, and an output coupled to the data input of the slave write latch150.

The slave write latch circuit 150 includes a third clocked inverter 152having a data input coupled to receive output from the second clockedinverter 146, a first clock input receiving the fifth clock outputCKSBB, and a second clock input receiving the fourth clock output CKSB.A second inverter 154 receive output from the third clocked inverter152. A fourth clocked inverter 156 has a data input coupled to receiveoutput from the second inverter 154, a first clock input receiving thefourth clock output CKSB, a second clock input receiving the fifth clockoutput CKSBB, and an output coupled to the multiplexer 160.

As will be understood by those of skill in the art, the above latchingof the read and write addresses have been described with reference toone bit. The above described master read latch circuit 130, master writelatch circuit 140, and slave write latch circuit 150 are replied foreach bit of the read and write addresses.

As can be seen, the read address RA<0:n> is always taken from the masterwrite latch 130. The write address WA<0:n> is taken from the slave writelatch 150, however, as shown through the use of the write only signalWRONLY in the address control circuit 110, and the subsequent generationof CKSB and CKSBB, the slave write latch 150 in the case of a write onlyoperation becomes transparent, as shown in FIG. 9. This enablessettlement of the write address to the row-decoder and to the IO block,before arrival of external clock CK to start a write operation.

Alternatively, as shown in FIG. 10, CKMBB and CKSBB can be generated aslarge pulses for the latches so as to cover completion of both the readand the write operations. When operating in pseudo-dual port mode, thereset for CKMBB and CKSBB can come from a write selftime reset.

Details of the row and column pre-decoder 106 will now be given withadditional reference to FIG. 6. The row and column pre-decoder 106includes a read latch 200 configured to selectively latch the readaddress RA<0:n> for output to the multiplexer 204, and a write latch 202configured to selectively latch the write address WA<0:n> for output tothe multiplexer 204. The multiplexer 204 in turn provides output of thelatched address A<0:n> to pre-decoder 206. The pre-decoder 206 splitsthe address A<0:n> into portions A, B, C, and D. A is fed throughinverter 216 to NAND gate 218, which also receives the intCK signal asinput. B is fed through inverter 212 to NOR gate 214. C is fed throughinverter 210 to NOR gate 214. D is fed to NAND gate 208, which alsoreceives the hold clock HCLK as input, and provides its output to NORgate 214.

PMOS transistor T5 has its source coupled to the power node VDD, itsdrain coupled to the drain of NMOS transistor T6, and its gate coupledto reset signal RESET. NMOS transistor T6 has its source coupled toreceive output from the NAND gate 218, and serves to output the decodedrow and column address, through inverter 222, to the row decoder 54, andread-write multiplexers 64, 62.

The use of the RC tracking performed by the YCLKRC TRACK is nowdescribed. The memory control circuitry 100 may operate under a widevariety of operational conditions and temperatures. In order forpseudo-dual port mode to properly function, the global signals withinthe memory array 58, should be reset properly prior to beginning of thewrite operation after the read operation.

Without tracking and compensating for the effects of parasiticcapacitances, failure states, such as shown in FIG. 11, may occur inwhich the intCK and hold clock HCLK are generated prematurely, resultingin changing of the address A<0:n> during a read operation prior tocompletion of the read operation. By utilizing RC tracking, as shown inFIG. 12, this failure mode is avoided.

The ability of the memory control circuitry 100 to switch dynamicallybetween pseudo-dual port mode and single port mode can be observed inFIG. 13. To operate in single mode, referring back to the port controlcircuitry 300, MUXSEL is forced to a logic high, passing WEN.

While the disclosure has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments can be envisionedthat do not depart from the scope of the disclosure as disclosed herein.Accordingly, the scope of the disclosure shall be limited only by theattached claims.

The invention claimed is:
 1. A memory controller for a memory arrayhaving word lines and bit lines, the memory controller comprising: a rowdecoder configured to decode a row address and select a word linecorresponding to the decoded row address; a row pre-decoder configuredto output an address to the row decoder as the row address, a read-writeclock generator configured to generate a hold clock signal; and anaddress clock generator configured to receive a read address, a writeaddress, a dual port mode control signal, a read chip select signal, anda write chip select signal; wherein the address clock generator, whenoperating in dual port mode as indicated by the dual port mode controlsignal, and when operating in a read mode as indicated by the read chipselect signal, is configured to latch the read address and output theread address to the row pre-decoder as the address as a function of thehold clock signal; and wherein the address clock generator, whenoperating in dual port mode as indicated by the dual port mode controlsignal, and when operating in a write mode as indicated by the writechip select signal, is configured to latch the write address and outputthe write address to the row pre-decoder as the address as a function ofthe hold clock signal.
 2. The memory controller of claim 1, wherein theaddress clock generator is configured to latch the write address foroutput prior to completion of a read operation.
 3. The memory controllerof claim 1, wherein the address clock generator is configured togenerate address clock signals; and wherein the row pre-decoder outputsthe address to the row decoder in response to the received address clocksignals.
 4. The memory controller of claim 3, wherein the address clockgenerator comprises: address control circuitry configured to receive theread chip select signal, and the write chip select signal, and inresponse thereto, generate the address clock signals and a multiplexer(mux) select signal; and a multiplexer configured to multiplex thelatched read address and to receive the latched write address to the rowpre-decoder as the address, in response to the mux select signal.
 5. Thememory controller of claim 4, wherein the address control circuitrycomprises: an address control block configured to receive the read chipselect signal, and the write chip select signal, and in responsethereto, generate a first clock output and a write only signal; acircuit block configured to generate the clock signals from the firstclock output and the write only signal.
 6. The memory controller ofclaim 5, wherein the circuit block comprises: a first inverter coupledto receive the first clock output and to generate therefrom a secondclock output; a second inverter coupled to receive the second clockoutput and to generate therefrom a third clock output; a NAND gateconfigured to receive the first clock output and the write only signaland to generate therefrom a fourth clock output; and a third invertercoupled to the output of the NAND gate to generate a fifth clock output.7. The memory controller of claim 5, wherein the address control blockcomprises: a first OR gate coupled to receive the read chip selectsignal and the write chip select signal; a first NOR gate coupled toreceive output from the first OR gate and the mux select signal; a firstlatch configured to receive output from the first NOR gate as input andbeing clocked by the hold clock signal; a first inverter configured toreceive output from the first latch; a second latch configured toreceive output from the first inverter; and a first NAND gate configuredto receive the write only signal, and output from the second latch, andto generate therefrom the mux select signal.
 8. The memory controller ofclaim 7, further comprising a second OR gate coupled to receive thewrite chip select signal and an inverted form of the read chip selectsignal, and to generate therefrom the write only signal.
 9. The memorycontroller of claim 6, further comprising: a read flip flop configuredto receive the read address and to latch the read address for output tothe multiplexer until completion of a read operation; a master writeflip flop configured to receive the write address; and a slave writeflip flop configured to receive output from the master write flip flopand configured to latch the write address for output to the multiplexersuch that the write address is already latched when a write operationbegins.
 10. The memory controller of claim 9, wherein the read flip flopcomprises: a first clocked inverter having a data input receiving theread address as input, a first clock input receiving the second clockoutput, and a second clock input receiving the third clock output; aninverter coupled to receive output from the first clocked inverter; anda second clocked inverter having a data input coupled to receive outputfrom the inverter, a first clock input receiving the third clock output,a second clock input receiving the second clock output, and an outputcoupled to the multiplexer.
 11. The memory controller of claim 9,wherein the master write flip flop comprises: a first clocked inverterhaving a data input receiving the write address as input, a first clockinput receiving the second clock output, and a second clock inputreceiving the third clock output; an inverter coupled to receive outputfrom the first clocked inverter; and a second clocked inverter having adata input coupled to receive output from the inverter, a first clockinput receiving the third clock output, a second clock input receivingthe second clock output, and an output; wherein the slave write flipflop comprises: a third clocked inverter having a data input coupled toreceive output from the second clocked inverter, a first clock inputreceiving the fifth clock output, and a second clock input receiving thefourth clock output; a second inverter coupled to receive output fromthe third clocked inverter; and a fourth clock inverter having a datainput coupled to receive output from the second inverter, a first clockinput receiving the fourth clock output, a second clock input receivingthe fifth clock output, and an output coupled to the multiplexer. 12.The memory controller of claim 1, wherein the read-write clock generatorcomprises: a first flop chain configured to receive the write chipselect signal and being clocked by a latch clock; a second flop chainconfigured to receive the read chip select signal and being clocked bythe latch clock; a first NOR gate coupled to receive output from thefirst and second flop chains; a first NAND gate coupled to receiveoutput from the first NOR gate; a latch chain receiving output from thefirst NAND gate and being clocked by a reset signal and a complementthereof; wherein the first NAND gate is also coupled to receive outputfrom the latch chain; a second NOR gate coupled to receive output fromthe latch chain and configured to receive a RC tracking signal; a firsttransistor having a first conduction terminal coupled to an internalclock node, a second conduction terminal coupled to ground, and a gateterminal coupled to receive output from the second NOR gate; and acircuit block coupled to the internal clock node and configured togenerate the hold clock signal.
 13. The memory controller of claim 12,further comprising a RC tracking circuit configured to assert the RCtracking signal when a write is completed and when a read is completed.14. The memory controller of claim 12, wherein the read-write clockgenerator further comprises: a second transistor having a firstconduction terminal coupled to a supply node, a second conductionterminal, and a gate terminal coupled to the reset signal; a thirdtransistor having a first conduction terminal coupled to the secondconduction terminal of the second transistor, a second conductionterminal, and a gate terminal coupled to receive an external clocksignal; and a fourth transistor having a first conduction terminalcoupled to the second conduction terminal of the third transistor, asecond conduction terminal coupled to ground, and a gate terminalcoupled to receive a delayed version of the external clock signal;wherein the second conduction terminal of the second transistor is alsocoupled to the internal clock node.
 15. The memory controller of claim1, wherein the row pre-decoder comprises: a write latch configured toselectively latch the write address; a read latch configured toselectively latch the read address; a pre-decoder block configured tooutput first, second, third, and fourth address fragments; a multiplexerconfigured to multiplex the write address and read address to thepre-decoder block; a first NAND gate configured to receive the holdclock signal and the fourth address fragment; a first inverterconfigured to receive the third address fragment; a second inverterconfigured to receive the second address fragment; and a first NOR gateconfigured to receive output from the first NAND gate, the firstinverter, and the second inverter.
 16. The memory controller of claim15, further comprising: a third inverter configured to receive the firstaddress fragment; a second NAND gate configured to receive an outputfrom the third inverter and a complement of an internal clock signal; afirst transistor having a first conduction terminal coupled to a supplynode, a second conduction terminal, and a gate coupled to a resetsignal; a second transistor having a first conduction terminal coupledto the second conduction terminal of the first transistor, a secondconduction terminal coupled to an output of the second NAND gate, and agate coupled to an output of the first NOR gate; and a fourth invertercoupled to the second conduction terminal of the first transistor andconfigured to output the row address to the row decoder.
 17. The memorycontroller of claim 1, wherein the memory array comprises an array ofSRAM cells, each SRAM cell comprised of six transistor in a sixtransistor SRAM arrangement.
 18. A memory controller for a memory arrayhaving word lines and bit lines, the memory controller comprising: aread-write clock generator configured to generate a hold clock signal;an address clock generator configured to receive a read address, a writeaddress, a read chip select signal, and a write chip select signal;wherein the address clock generator, when operating in a read mode asindicated by the read chip select signal, is configured to apply a readdelay to the read address and output the read address, as delayed, as anaddress, in response to the hold clock signal; and wherein the addressclock generator, when operating in a write mode as indicated by thewrite chip select signal, is configured to apply a write delay to thewrite address and output the write address, as delayed, as an address,prior to completion of a read operation, in response to the hold clocksignal.
 19. The memory controller of claim 18, wherein the read-writeclock generator comprises: a first flop chain configured to receive thewrite chip select signal and being clocked by a latch clock; a secondflop chain configured to receive the read chip select signal and beingclocked by the latch clock; a first NOR gate coupled to receive outputfrom the first and second flop chains; a first NAND gate coupled toreceive output from the first NOR gate; a latch chain receiving outputfrom the first NAND gate and being clocked by a reset signal and acomplement thereof; wherein the first NAND gate is also coupled toreceive output from the latch chain; a second NOR gate coupled toreceive output from the latch chain and configured to receive a RCtracking signal; a first transistor having a first conduction terminalcoupled to an internal clock node, a second conduction terminal coupledto ground, and a gate terminal coupled to receive output from the secondNOR gate; and a block coupled to the internal clock node so as togenerate the hold clock signal.
 20. The memory controller of claim 19,further comprising a RC tracking circuit configured to assert the RCtracking signal when a write is completed and when a read is completed.21. The memory controller of claim 19, wherein the read-write clockgenerator further comprises: a second transistor having a firstconduction terminal coupled to a supply node, a second conductionterminal, and a gate terminal coupled to the reset signal; a thirdtransistor having a first conduction terminal coupled to the secondconduction terminal of the second transistor, a second conductionterminal, and a gate terminal coupled to receive an external clocksignal; and a fourth transistor having a first conduction terminalcoupled to the second conduction terminal of the third transistor, asecond conduction terminal coupled to ground, and a gate terminalcoupled to receive a delayed version of the external clock signal;wherein the second conduction terminal of the second transistor is alsocoupled to the internal clock node.